First, you are not alone. Many FTs (including me) are looking for available J space to Europe this summer. My "advice" is to be prepared to buy P fares (I bought two to MXP). By comparison, the surcharges and taxes on the route are for AP seats are in excess of $1 K - so P fares look pretty reasonable by comparison.

Currently, LOT has a sale on fares to Europe. Transiting YYZ on a new 787-9.

Transiting YUL is another option. BTW, taxes are lower than on fares via YYZ.

I am seeing some J reward availability on LH. Another option.

If you are still looking for 2 reward seats, you may have to accept separate itinerary's.

You did not mention Rouge. Am seeing Rouge flights pop up 1st on AP searches. I (& many others) will avoid Rouge at any cost. Having said that, AC has boosted Rouge capacity this summer via BUD, VCE.

Finally, what about SEA? I don't share your concerns about transiting USA but it is a lot easier to do via Amtrak than on an aircraft.